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91.
B. Monchev D. Filenko N. Nikolov C. Popov T. Ivanov P. Petkov I.W. Rangelow 《Applied Physics A: Materials Science & Processing》2007,87(1):31-36
Thin amorphous Ge–S–AgI films were thermally evaporated on cantilever sensors and their sorption properties were investigated
upon exposure to volatile analytes, such as water, ethanol, acetone, and ammonia vapours. The films were smooth and uniform
in thickness as revealed by atomic force and scanning electron microscopies. The exposure to the analytes resulted in a change
of the resonance frequency of the cantilever. Initially, the largest dynamic responses (frequency shifts) were observed towards
acetone, i.e. the cantilever acted as a resonant microbalance. When the sensor was exposed to ammonia, its molecules were
chemisorbed on the surface of the sensitive layer. This surface modification increased the sensor sensitivity towards water
molecules by the creation of new interaction sites.
PACS 81.05.-t; 85.85.+j; 07.07.Df 相似文献
92.
A. Małecki A. N. Antonov I. Zh. Petkov P. E. Hodgson 《Zeitschrift für Physik A Hadrons and Nuclei》1987,328(4):393-397
The relation between the nuclear spatial and momentum densities is studied by means of their integral representations in terms of uniform distributions. Examples of this approach are given for the harmonic oscillator model of4He and16O, with and without Jastrow correlations, and for the single-particle potential model of40Ca. 相似文献
93.
94.
Koleva BB Stoyanov S Kolev T Petkov I Spiteller M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(3):847-853
Structural and spectroscopic elucidation of merocyanine dye, 2,5-[1-metyl-4-[2-(4-hydroxyphenyl)ethenyl)]piridinium]-hexane tetraphenylborate, is performed in gas and condense phase by means of solution and solid-state conventional and linear-polarized IR-spectroscopy of oriented colloids in nematic liquid crystal suspension, UV-vis and fluorescence methods, HPLC MS/MS tandem and ESI mass spectrometry, (1)H, (13)C and (1)H-(1)H COSY NMR, TGV and DSC methods. Quantum chemical DFT calculations are performed for structural optimization and spectroscopic properties prediction. 相似文献
95.
The paper reports on the dependence of the absorbance and luminescent intensity from pH of novel poly(oxyethylene phosphate)
tris(β-diketonate) europium (III) complexes. The photophysical data obtained allow some preliminary assumptions about the
nature of this phenomenon. Increase in luminescent efficiency is a consequence of enhanced efficiency of energy transfer caused
by structural changes in complexes after water deprotonation. Remarkable change has been observed in photophysical properties
of the polymer complexes by studying the fluorescent emission and excitation spectra and absorption recorded at various pH
both in solution and in the solid state. Some of the complexes derivative of the dibenzoylmethane (DBM) show more than hundred
times increase in the luminescence after alkalization. The pH value, at which the maximum luminescent efficiency appears,
depends on the type of the fourth ligand. The difference between luminescent efficiency of the complexes in alkaline and neutral
environment depends on the β-diketonate ligands and on polymer type as well.
相似文献
96.
Sevan Chanakian Wanyue Peng Vanessa Meschke A. K. M. Ashiquzzaman Shawon Jesse Adamczyk Valeri Petkov Eric Toberer Alexandra Zevalkink 《Angewandte Chemie (International ed. in English)》2023,62(29):e202301176
AMX compounds with the ZrBeSi structure tolerate a vacancy concentration of up to 50 % on the M-site in the planar MX-layers. Here, we investigate the impact of vacancies on the thermal and electronic properties across the full EuCu1−xZn0.5xSb solid solution. The transition from a fully-occupied honeycomb layer (EuCuSb) to one with a quarter of the atoms missing (EuZn0.5Sb) leads to non-linear bond expansion in the honeycomb layer, increasing atomic displacement parameters on the M and Sb-sites, and significant lattice softening. This, combined with a rapid increase in point defect scattering, causes the lattice thermal conductivity to decrease from 3 to 0.5 W mK−1 at 300 K. The effect of vacancies on the electronic properties is more nuanced; we see a small increase in effective mass, large increase in band gap, and decrease in carrier concentration. Ultimately, the maximum zT increases from 0.09 to 0.7 as we go from EuCuSb to EuZn0.5Sb. 相似文献
97.
Lukas Sporrer Dr. Guojun Zhou Dr. Mingchao Wang Dr. Vasileios Balos Sergio Revuelta Kamil Jastrzembski Dr. Markus Löffler Prof. Dr. Petko Petkov Prof. Thomas Heine Dr. Angieszka Kuc Prof. Dr. Enrique Cánovas Dr. Zhehao Huang Prof. Dr. Xinliang Feng Prof. Dr. Renhao Dong 《Angewandte Chemie (International ed. in English)》2023,62(25):e202300186
Two-dimensional conjugated metal–organic frameworks (2D c-MOFs) are emerging as a unique class of electronic materials. However, 2D c-MOFs with band gaps in the Vis-NIR and high charge carrier mobility are rare. Most of the reported conducting 2D c-MOFs are metallic (i.e. gapless), which largely limits their use in logic devices. Herein, we design a phenanthrotriphenylene-based, D2h-symmetric π-extended ligand ( OHPTP ), and synthesize the first rhombic 2D c-MOF single crystals ( Cu2(OHPTP) ). The continuous rotation electron diffraction (cRED) analysis unveils the orthorhombic crystal structure at the atomic level with a unique slipped AA stacking. The Cu2(OHPTP) is a p-type semiconductor with an indirect band gap of ≈0.50 eV and exhibits high electrical conductivity of 0.10 S cm−1 and high charge carrier mobility of ≈10.0 cm2 V−1 s−1. Theoretical calculations underline the predominant role of the out-of-plane charge transport in this semiquinone-based 2D c-MOF. 相似文献
98.
M. M. Kochkarov I. A. Alikhanov M. M. Boliev I. M. Dzaparova R. V. Novoseltseva Yu. F. Novoseltsev V. B. Petkov V. I. Volchenko G. V. Volchenko A. F. Yanin 《Physics of Particles and Nuclei》2016,47(6):980-985
Preliminary results of a neutron background measurement at the Baksan underground scintillation telescope (BUST) are presented. The external planes of the BUST are fully covered with standard scintillation detectors shielding the internal planes and suppressing thus background events due to cosmogenic and local radioactivity. The shielded internal planes were used as target for the neutron flux registration. The experimental method is based on the delayed coincidences between signals from any of the BUST counters. It is assumed that the first signal is due to inelastic interaction of a neutron with the organic scintillator, while the second signal comes from the decay of an unstable radioactive isotope formed when the fast neutron interacts with the 12C nuclei. Using the Monte-Carlo method (GEANT4) we also simulated propagation of neutrons through a layer of scintillator. The experimentally found muon induced neutron flux is j =1.3-0.3+0.7 ×10-10cm-2s-1 for neutron energies E ≥ 22MeV, which is in a qualitative agreement with similar measurements of other underground laboratories as well as with predictions of the GEANT4. 相似文献
99.
R. V. Novoseltseva M. M. Boliev I. M. Dzaparova M. M. Kochkarov Yu. F. Novoseltsev V. B. Petkov V. I. Volchenko G. V. Volchenko A. F. Yanin 《Physics of Particles and Nuclei》2016,47(6):968-974
The current status of the experiment on recording neutrino bursts from core collapse stars is presented. The actual observational time is 29.76 years. An upper bound of the mean frequency of core collapse supernovae in our Galaxy is fcol < 0.077 year–1 (90% CL). 相似文献
100.
St Petkov P Vayssilov GN Krüger S Rösch N 《The journal of physical chemistry. A》2007,111(11):2067-2076
With a gradient-corrected density functional method, we have studied computationally the influence of single impurity atoms on the structure, electronic, and magnetic properties of Ni5 clusters. The square-pyramidal isomer of bare Ni5 with six unpaired electrons was calculated 23 kJ/mol more stable than the trigonal bipyramid in its lowest-energy electronic configuration with four unpaired electrons. In a previous study on the cluster Ni4, we had obtained only one stable isomer with an O or an H impurity, but we located six minima for ONi5 and five minima for HNi5. In the most stable structures of HNi5, the H atom bridges a Ni-Ni edge at the base or the side of the square pyramid, similarly to the coordination of an H atom at the tetrahedral cluster Ni4. The most stable ONi5 isomers exhibit a trigonal bipyramidal structure of the Ni5 moiety, with the impurity coordinated at a facet, (micro3-O)Ni5, or at an apex edge, (micro-O)Ni5. We located four stable structures for a C impurity at a Ni5 cluster. As for CNi4, the most stable structure of the corresponding Ni5 complex comprises a four-coordinated C atom, (micro4-C)Ni5, and can be considered as insertion of the impurity into a Ni-Ni bond of the bare cluster. All structures with C and five with O impurity have four unpaired electrons, while the number of unpaired electrons in the clusters HNi5 varies between 3 and 7. As a rough trend, the ionization potentials and electron affinities of the clusters with impurity atoms decrease with the coordination number of the impurity. However, the position of the impurity and the shape of the metal moiety also affect the results. Coordination of an impurity atom leads to a partial oxidation of the metal atoms. 相似文献